Images of salt flats and bleached steer skulls are part of western movie lore. Fortunately, there are few acres of land this barren due to excess salts. However, pockets of salty land and salty well water can create plant growing challenges in both the plains and mountain areas of Colorado.
Gardeners should suspect excessive salts if plants are stunted with brown leaf edges, if seeds fail to germinate, and flower and fruit yields are poor. A soil test must be done to confirm if salts are the problem, since other environmental factors can cause similar symptoms.
Chemicals cannot be added to the soil to solve the problem. The remedy for salt-affected soils is twofold. First, improve soil drainage then secondly, water heavily to dissolve and wash salts from the soil.
You can improve soil drainage through cultivation, taking special care to break up subsoil hardpan layers that prevent water movement. Hardpans are caused by using machine tillers at the same depth time after time. Mineral layers such as gypsum can also create soil which is impermeable to water. Use a shovel, pick or bar to break holes in these mineral layers for drainage.
Note that adding organic amendments such as peat or compost to salty, poorly drained soils can make matters worse. The amendments act like a sponge to hold salts, which burn and kill plant roots. The cause of the poor drainage must be determined and remedied before mixing in organic soil amendments.
Once the drainage problems are solved, irrigate the soil slowly for a long time to prevent surface runoff. The water will dissolve salts and the salty water will drain. In extreme cases, you will need to plant salt tolerant landscape plants, or create raised berms or beds on top of landscape fabric which will prevent salts from wicking into the raised soil.
For more information, see the following Colorado State University Extension fact sheet(s).
- Managing Saline Soils
- Vegetable garden: Soil Management and Fertilization
- Growing Turf on Salt-Affected Sites
- Choosing a Soil Amendment